Corolla retention after pollination facilitates the development of fertilized ovules in Fritillaria delavayi (Liliaceae)

Corollas (or perianths), considered to contribute to pollinator attraction during anthesis, persist after anthesis in many plants. However, their post-floral function has been little investigated within a cost-benefit framework. We explored the adaptive significance of corolla retention after anthesis for reproduction in Fritillaria delavayi, a perennial herb endemic to the alpine areas of the Hengduan Mountains, southwestern China. We examined whether the persistent corollas enhance reproductive success during seed development. Persistent corollas increased fruit temperature on sunny days, and greatly decreased the intensity of ultraviolet-B/C (UV-B/C) radiation reaching fruits. When corollas were removed immediately after pollination, fecundity and progeny quality were adversely affected. Measurements of flower mass and size showed no further corolla growth during fruiting, and respiration and transpiration tests demonstrated that both respiration rate and transpiration rate of corollas were much lower during fruiting than during flowering, indicating a slight additional resource investment in corolla retention after anthesis. Thus, seed production by F. delavayi may be facilitated by corolla retention during seed development at only a small physiological cost. We conclude that corolla retention may be an adaptive strategy that enhances female reproductive success by having a protective role for ripening seeds in the harsh conditions at high elevation.